Expression of a single fair of desmosomal glycoproteins readers the corneal epithelium unique amongst stratified epithelia

PURPOSE. To determine desmosomal glycoprotein isoform expression in bovine corneal, limbal, and conjunctival epithelium and desmosomal profile and dis tribution during corneal re-epithelialization. METHODS. Immunofluorescence (IF) for desmosomal components on cryostat sect ions of fresh epithelia was supported by immunoblot analysis of tissue lysa tes. Wounded corneas maintained in organ culture were examined by IF at tim es up to full re-epithelialization (96 hours). RESULTS. Immunofluorescence for desmoplakin confirmed desmosome presence th roughout all three epithelia. Plakoglobin was also ubiquitous. Of the desmo somal glycoproteins, desmocollin 7 (Dsc2) and desmoglein 2 (Dsg2) were expr essed throughout, but Dsc3 and Dsg3 were confined to the limbus and conjunc tiva, and Dsc1 and Dsg1 were absent. Dsc2 and Dsg3 Ifs were stronger in sup erficial layers, but Dsc3 and Dsg3 were stronger basally, fading suprabasal ly. Glycoprotein expression in cornea and conjunctiva was confirmed by immu noblot analysis. No change in glycoprotein expression occurred during re-ep ithelialization. CONCLUSIONS. Uniquely among stratified epithelia, cornea expresses only a s ingle pair of desmosomal glycoproteins, Dsc2 and Dsg2. Expression of Dsc3 a nd Dsg3 in limbus and conjunctiva coincides with their association with cel l proliferation in other epithelia, bur corneal epithelial cells did not ex press Dsc3 or Dsg3 during re-epithelialization. Absence of Dsc1 and Dsg1 co rrelates with lack of keratinization in ocular epithelia. These expression patterns may have significance for the specific properties and differentiat ion patterns of the epithelia. Presence of desmosomes throughout re-epithel ialization raises the question of how migrating cells mutually re-position.